Since the mid-1990s, many studies have shown the effectiveness of "High Interval Training" (HIT) for fat loss. One Canadian study compared the fat-loss effects of interval training versus a traditional, slow cardio regimen. The traditional regimen burned twice as many calories as the interval regimen, but those who performed intervals lost more body fat.

Researchers from the City of Eugene’s FitCity Wellness Center in Oregon recruited 21 mostly active adults to participate in a HIIT group exercise program three times per week for 10 weeks. Each class included a brief warm-up and then body weight exercises following a two-to-one work-to-rest ratio. The average class lasted just over 27 minutes, and participants were encouraged to take minibreaks outside the structured rest periods if necessary.

At the end of the study, participants showed reductions in body weight, body fat percentage and body mass index. There was a slight increase in fat-free mass. The group also experienced reductions in circumference measurements of the upper arms, chest, waist, hips and calves. Thigh measurements changed very little.

“HIIT three days per week for 10 weeks produced significant reductions in body weight, BMI, body fat percentage and body circumference measurements except for the thighs,” explained study author Steven J. Auferoth, director of health and wellness for the center.

Auferoth believes HIIT could be a boon for fitness instructors, personal trainers and fitness facilities, owing to its potential to help clients make significant physiological improvements in a time-efficient manner. Professionals might also see a bump in revenue, since the short time investment makes it possible to see more clients per hour.(Halvorson, 2013)

Halvorson, R. (2013, September 19). The benefits of group high-intensity interval training. Retrieved October 28, 2016, from http://www.ideafit.com/fitness-library/the-benefits-of-group-high-intensity-interval-training